Heat Index Calculator
How hot it feels when humidity limits sweat evaporation, with heat-risk categories.
Feels like (°C)
40.40
Breakdown
- Feels like (°F)
- 104.70
- Heat risk
- Danger — heat cramps/exhaustion likely
Last updated:
FAQ
What is the heat index?
The apparent temperature the body perceives when high humidity slows sweat evaporation, computed with the NWS Rothfusz regression.
At what heat index is it dangerous?
Above roughly 32°C apparent temperature the risk shifts to danger — heat cramps and exhaustion become likely with prolonged activity.
Why does humidity make heat worse?
Sweat can only cool you if it evaporates; saturated air stalls evaporation, so the body gains heat instead of losing it.
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